The present invention relates to radiation sources, and more particularly to an orientation dependent radiation source, the orientation of which may be determined about one or more axes of rotation.
Conventional radiation sources include xe2x80x9cprimaryxe2x80x9d sources, such as acoustic or electromagnetic wave transmitters, as well as xe2x80x9csecondaryxe2x80x9d sources of radiation, such as reflectors which reflect radiation based on some incident radiation. While both conventional primary and secondary radiation sources are employed in a wide variety of applications, many conventional sources are not constructed so as to facilitate a determination of an orientation of the source, or an orientation of an object to which the source is coupled, with respect to some reference position.
In particular, conventional primary orientation dependent sources which direct radiation to a particular observation area and facilitate the determination of the orientation of the source from the observation area are not known. Moreover, conventional orientation detection systems, which employ secondary radiation sources such as reflectors, are mostly limited to the determination of orientation in a single dimension, or about one axis of rotation. Many conventional orientation detection systems, including those systems which are constructed so as to facilitate a determination of orientation in more than one dimension, typically employ complex image processing techniques and equipment which process signals that are received from a group of radiation sensors arranged in a line, or dispersed throughout an observation area. Such radiation sensing configurations are often expensive and may require large observation areas for deployment, rendering such orientation detection systems impractical for many applications.
The present invention is directed to methods and apparatus for producing orientation dependent radiation, and orientation detection systems employing such methods and apparatus.
In one embodiment, an orientation dependent radiation source according to the invention includes a first mask to substantially block radiation, wherein the first mask defines an observation surface and includes a first plurality of openings through which radiation is capable of passing. The orientation dependent radiation source also includes a second mask coupled to the first mask. The second mask includes a second plurality of openings offset relative to the first plurality of openings such that radiation passing through at least the first plurality of openings produces an orientation dependent radiation pattern on the observation surface. The orientation dependent radiation pattern has at least one detectable centroids that varies in position across the observation surface based on a rotation angle of the first and second masks about at least one axis of rotation.
In another embodiment, an orientation detection system according to the invention includes one or more orientation dependent radiation sources to direct orientation dependent radiation to an observation area. Each orientation dependent radiation source is constructed and arranged so as to facilitate a determination, from the observation area, of a rotation angle of the source about at least one axis of rotation based on the orientation dependent radiation. The system also includes one or more radiation sensors located within the observation area to detect the orientation dependent radiation. In one embodiment of the orientation detection system according to the invention, each orientation dependent radiation source includes a primary radiation source.
A method for producing an orientation dependent radiation pattern on an observation surface, according to one embodiment of the invention, includes a step of varying a surface area of a radiation source exposed through the observation surface, in response to a rotation of the observation surface about at least one axis of rotation, to produce at least one detectable centroids having a position that varies across the observation surface corresponding to the rotation.
Other advantages, novel features and objects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.